103 Name Locker NumberDate REPORT SHEET Experiment 7 Hydrat

103 Name %, Locker NumberDate REPORT SHEET: Experiment 7 Hydrates and the Determination of the Formula of a Hydrate A. Determining the Percent Water and the Formula of a Hydrate NrS Unknown number: A Trial 2 is to be carried out if the results of trial 1 are unsatisfactory Trial 1 Trial 2 Mass of crucible + lid + unknown Mass of crucible +lid Mass of unknown hydrate Mass of crucible +lid + residue... 259 74 .. . after first heating after second heating .. after third heating Mass of anhydrous salt Mass of water lost Percent water in unknown hydrate Formula of unknown hydrate (from your instructor) Moles of water in the hydrate sample oles of anhydrous salt in the hydrate sample mplete formula of the hydrate -O i S 7

Solution

Since 17% of the total sample is water, so 0.17 x 2g =0.34 g of water is present in 2 gm of the sample.

Therefore moles of water in the hydrate sample= 0.34/18 moles =0.0188 mole

Now, moles of anhydrous salt in the hydrate sample = (2-0.34)/molar mass = 1.66/154.75 = 0.0107 mole

Therefor complete formula of the hydrate is (NiSO₄)_0.0107.(H₂O)_0.0188  i.e NiSO₄.2H₂O